KNOXVILLE, Tenn. (WVLT) -- Researchers at the National Institute for Mathematical and Biological Synthesis (NIMBioS), based at UT, think they may be on the way to solving the long-running question: Is homosexuality genetic?

"Previous studies have shown that homosexuality runs in families, leading most researchers to presume a genetic underpinning of sexual preference," said Sergey Gavrilets, paper co-author, joint professor of math and ecology and evolutionary biology and NIMBioS's associate director for scientific activities. "However, no major gene for homosexuality has been found despite numerous studies searching for a genetic connection."

The answer, they say, may lie epi-genetics - how gene expression is regulated by temporary switches. They found epi-marks, which make up an extra layer of information attached to the genes' backbones and regulate their expression, could be the trigger they were looking for.

"Transmission of sexually antagonistic epi-marks between generations is the most plausible evolutionary mechanism of the phenomenon of human homosexuality," said Gavrilets.

In the study, researchers found that sex specific epi-marks, which are normally "erased" and do not pass between generations, can cause homosexuality when they are not erased and are transmitted from father to daughter or mother to son.

"We discovered when these epi-marks are transmitted across generations from fathers to daughters or mothers to sons, they may cause reversed effects, such as the feminization of some traits in sons, such as sexual preference, and similarly a partial masculinization of daughters," said Gavrilets.

The paper is co-authored with William Rice, a professor at the University of California, Santa Barbara, and Urban Friberg, a professor at Uppsala University in Sweden.

Online Public Information File

Viewers with disabilities can get assistance accessing this station's FCC Public Inspection File by contacting the station with the information listed below. Questions or concerns relating to the accessibility of the FCC's online public file system should be directed to the FCC at 888-225-5322, 888-835-5322 (TTY), or fccinfo@fcc.gov.